Topline
Have you seen the green comets yet? Two icy visitors from the edge of the solar system — Comet Lemmon (C/2025 A6) and Comet SWAN (C/2025 R2) — are the first comets visible in binoculars since Comet Tsuchinshan-ATLAS in October 2024. Both are visible after sunset on Wednesday, Oct. 22, 2025, from the Northern Hemisphere, remaining near their brightest in the night sky. It’s an especially good night to catch Comet Lemmon, which will sit just to the right of Izar in the constellation Boötes, above the orange star Arcturus. Comet SWAN glows directly below Altair, the uppermost star of the Summer Triangle.
Comet Lemmon (C/2025 A6) as imaged by Gianluca Masi at The Virtual Telescope Project (www.virtualtelescope.eu).
Gianluca Masi at The Virtual Telescope Project (www.virtualtelescope.eu).
Key Facts
Although both Lemmon and SWAN reached their brightest on Monday, Oct. 20, when they reached their closest to Earth at 55 and 24 million miles, respectively, they are likely to remain at their brightest on Wednesday, Oct. 22.
The comets are visible in the northwest (Lemmon) and southwest (SWAN) about 90 minutes after sunset. Lemmon is moving quickly across the sky west of the Big Dipper, close to bright star Arcturus, while SWAN is beneath the three bright stars that comprise the Summer Triangle.
The best way to find the comets is stargazing apps such as Sky Guide, Stellarium and SkySafari, or the finder charts at In-The-Sky.com.
Comet Lemmon and Comet SWAN are most easily seen using binoculars and away from light pollution in a Dark Sky Place (or somewhere that looks dark on a light pollution map). You may be able to see them with the naked eye, but binoculars will be required to see their tails.
Increasing moonlight will make both comets harder to see by the weekend, by which time both will have faded slightly, which makes this week the time to look. As always, comets can have a surprise outburst and brighten or a sudden disintegration and fade.
How to find Comet Lemmon, 90 minutes after sunset, from Oct. 13-24, 2025.
Stellarium
When And Where To See The Comets
The best time to spot Comet Lemmon and Comet SWAN on Wednesday, Oct. 22, is during a 30-minute window starting about 90 minutes after sunset where you are. Both are visible after sunset but in opposite parts of the sky — Lemmon in the northwest, SWAN in the southwest. For New York City, where sunset is at 6:02 p.m. EDT, the ideal time for evening viewing is 7:32-8:02 p.m. EDT. A 2%-lit waxing crescent moon sets early, barely even noticed, leaving a dark sky ideal for spotting the comets.
Where to find Comet Lemmon after sunset on Oct. 22, 2025.
Stellarium
How To Find Comet Lemmon
Distance from the sun: 61.6 million miles (99.1 million kilometers)
Distance from Earth: 55.7 million miles (89.6 million kilometers)
After sunset on Wednesday, Oct. 22, look for Comet Lemmon immediately above bright star Arcturus, low on the northwest horizon. Luckily, there’s a simple star-hop for that — just trace the stars in the Big Dipper’s curved handle and go in an “arc to Arcturus.” Now go a couple of degrees above Arcturus to the next bright star, Izar. Comet Lemmon will be just to the right side of Izar, about 19 degrees above the northwest horizon at 7:32 p.m. EDT. It will gradually sink as twilight deepens.
How to find Comet Lemmon, 90 minutes after sunset, from Oct. 13-31, 2025.
Stellarium
How To Find Comet Swan
Distance from the sun: 94.8 million miles (152.5 million kilometers)
Distance from Earth: 24.9 million miles (40.1 million kilometers)
Blueish-green Comet SWAN will be visible in binoculars on Wednesday, Oct. 22, 2025, low in the southwest after sunset. SWAN will be in the constellation Aquila, above the famous “Teapot” asterism in the constellation Sagittarius, and directly below the bright star Altair in the Summer Triangle. The comet’s height above the horizon will vary depending on your location, but from New York, it will be around 40 degrees up as it becomes visible.
Both comets will remain visible for another few evenings, but bright moonlight will quickly begin to wash them out by the weekend.
Where to find Comet SWAN after sunset on Oct. 22, 2025.
Stellarium
Check my feed every day this month for a daily “comet tracker” with finder charts and tips for viewing Comet Lemmon and Comet SWAN from mid-northern latitudes. Also read How To Photograph The Green Comets, Best Stargazing Apps For Finding The Comets and 25 Dark Sky Parks In The U.S. To See The Comets.
